Dr. Hartman uses color codes for personality because color is already an established metaphor for emotion and behavior. We "see red" when we're angry. We "feel blue" when we're sad.
Using this color guide to personality, you will be able to "see" the motives behind their own and other people's behavior, which will help anyone establish and maintain relationships with greater ease. They will be able to accept others for what they are. And, most important, they will learn to incorporate within themselves the best of all the colors of life.